Insulin pumps are thought to improve glucose metabolic control and reduce long-term complications compared to conventional therapy or even compared to multiple daily injections (MDI) therapy. While both continuous subcutaneous insulin infusion (CSII) and MDI fail to reproduce the physiological delivery of insulin exactly, depositing insulin into the subcutaneous tissue instead of the hepatic portal vein, CSII allows one to program changes in basal insulin dosage according to anticipated need and thereby reduce blood glucose variability. This is perhaps the one greatest advantage of CSII. As such, CSII is increasingly used as a means of insulin delivery for those with type 1 diabetes as CSII improves glycaemic control compared to other intensified insulin regimens. CSII makes it possible to better mimic physiological meal related insulin infusion profiles by infusion of time-varying insulin profiles even if this possibility is not exploited by classical methods to control post prandial glucose excursions.
Indeed, with both MDI and CSII, controlling blood glucose excursions after meals is the main challenge for the otherwise more controlled metabolism of a person with diabetes. Classical therapy methods based on insulin administration use a single-shot bolus to correct for the meals. This bolus is calculated on the basis of the meal carbohydrate contents. The dependency of absorption speed on type and size of a meal is not taken into account by the classical therapy method. Therefore differences between “slow” and “fast” absorbing meals are ignored leading to suboptimal control of blood glucose (e.g. and generally speaking, high BG values after meals, e.g. 300 mg/dl, or episodes of hypoglycaemia, are clear indicators of poor control).
Classical therapy methods and systems consider only carbohydrate content and carbohydrate/insulin sensitivity, thereby failing to account for meal composition, size, and absorption speed. This results in inferior control and management of blood glucose. In addition, classical therapy methods and systems consider only customization of insulin dosage, and not the pattern (i.e., dosing amount and timing sequence) of infusion that may provide the best treatment to a diabetic patient. In addition, classical therapy methods only compute meal size dependent single-shot boluses to control post prandial glucose excursions and do not consider time-varying insulin profiles which would provide the best treatment to a person with diabetes.